The good folks are Playlist have posted a review of The Complete U2:
On the other hand, because The Complete U2 contains every album and single, a good number of the “445 tracks” are duplicates. Not just slightly different versions, but identical copies. For example, the single version of “One” appeared on the album Achtung Baby, the single One, and the compilation The Best Of 1990-2000, so it appears three times in the box set. But it’s not the only one — a quick survey reveals at least 23 songs that have two identical versions in the set, and another 12 that have three identical versions. (There may be others, as well — these numbers come from comparing identical files. Sometimes the same song appears one or two seconds longer or shorter when included on a different album, so these numbers may be higher.) Perhaps the “445 track” tally should more realistically be listed as 398?
An interesting read to be sure, especially that bit about duplicate songs.